1. Field of Invention
The present invention relates to a lighting fixture, and more particularly to a lighting fixture, wherein the light projection angle of the lighting fixture is adjustable.
2. Description of Related Arts
It is always needed to affix some object onto a bracket or platform with a desired angle, for example, to affix a light to a bracket with a predetermined angle to light a particular area. Traditionally, screw and nut are used. For example, a light is affixed by using a screw to install from the hinge through a U-shaped bracket. The end of the screw is tightened up with a nut in order to secure the hinge, and the U-shaped bracket in position. The fixture angle can be adjusted by loosening the nut, and re-tightening the nut for fixing the fixture angle. The problem is: the tightening force for fixing the angle comes from the friction force between the screw, hinge, bracket, and the nut. There are three interfaces, and if either interface loses the friction, the fixture angle will not be kept. It is well know, the friction force is relatively small, and in order to increase friction force, the normal force of the interface must be increased, which means the screw and the nut have to be tightened largely. This introduces inconvenience to adjust the angle. And if the angle is adjusted frequently, the interfaces and the teeth of the screw and the nut will be worn out quickly, and can not work longer. This also request higher quality of the material of the screw, net, hinge and bracket.
To avoid the weakness of the traditional method, it is necessary to develop a new device to affix the object with a desired angle which is not using the friction force.